Such gas bags or air bags were arranged, at first, in the steering wheel of the vehicle, later to be supplemented by the so-called front-passenger air bag, they since having become standard also as side air bags on a series of vehicle types. Further air bags for specific impact areas or situations are now in development which are likewise already being offered by automotive manufacturers as an optional or even standard fitting.
In steering wheel air bag modules, since having become most developed, the propellant charge on nearly all models is accommodated in a cylindrical housing having gas exit ports. Only a few housing shapes, hardly differing from each other, have been developed due to the requirements dictated by rational production and safety standards in handling pyrotechnical material, as a result of which the outer shape of the air bag modules and the space to be made available for installation thereof are dictated by the shape of the housing for the pyrotechnical propellant charge. This is why, in general, a steering wheel needs to be completely newly designed in accommodating an air bag module, the same applying also to all other installation locations in the body of the vehicle, of course, which need to be reconfigured more or less for the installation of an air bag module. The considerable additional costs involved contrast with the desired further improvement in the passive safety in motor vehicles.
The invention provides a vehicular restraint system that obviates the limitations involved in usual housing shapes for a pyrotechnical propellant charge so that air bag modules may be designed more freely and easier to adapt to existing installation spaces.
According to one aspect of the invention, the vehicular restraint system comprises an inflatable gas bag defining an internal volume and a gas generator with a pyrotechnic propellant charge for generating gas upon inflation of the gas bag. The propellant charge comprises a mass of a pyrotechnic material. The mass includes a binding agent conglomerating the mass into a rigid shaped body . The body has a surface exposed to the internal volume of the gas bag.
According to a further aspect of the invention the vehicular restraint system comprises an inflatable gas bag defining an internal volume and a gas generator with a pyrotechnic propellant charge for generating gas upon inflation of the gas bag. The propellant charge comprises a mass of a pyrotechnic material. The mass is filled into a flexible envelope which has a surface exposed to the internal volume of the gas bag.
As an alternative it is proposed that in employing a suitable binding agent the complete mass of the pyrotechnical propellant is conglomerated into a one-piece, kneadable shaped body capable of being pressed into an available installation space.
Configuring the pyrotechnical. propellant charge for generating filling gases for instantly inflating a gas bag in accordance with the invention as a rigid or plastic shaped body enables it to be adapted to or kneaded into the available space substantially easier, this generally having the effect that the available space for installation needs to be altered either not at all or only slightly and that the air bag module as a rule necessitates only little space for installation since dead space, formerly not made use of or hardly at all, may now be put to use fully or in part. In addition to this there is now no need for the housing usually to be of steel, as a result of which the air bag module becomes much lighter in weight.
The necessary ignition device may now be integrated easier in the shaped body in accordance with the invention. In a further embodiment of the gist of the invention it is provided for that the shaped body comprises an envelope of paper, textile material, plastic foil or some other easily fashionable sheet material, whereby this envelope is not intended to replace the hitherto conventional rigid housing but simply to supplement the function of the binding agent and to prevent crumbling and uncontrolled loss of propellant charge particles from the shaped body in handling.
Another advantage afforded by the invention is that the mass of the propellant charge may now be easily distributed to two or more shaped bodies, to each of which an ignition device is assigned, thus enabling the consumption response to be influenced and deployment of the gas bag to be controlled.